The present invention refers to a process for manufacturing paper having a pleasant and unique dotted pattern which readily identifies its origin, using seaweed. The following description refers especially to paper, though the process described is equally useful for the manufacture of cardboard which is therefore included as part of this invention.
One of the greatest ecological problems affecting life in enclosed or semi-closed seas, and especially in the Mediterranean and Adriatic Seas, consists of presence of huge quantities of algae. The superabundance of these organisms caused by eutrophy of the waters due to domestic, agricultural and industrial waste, creates problems for both fish and seaside tourism.
The gathering of seaweed undertaken with special boats is a method now being used to eliminate or at least reduce the quantities of algal material formed, especially near beaches and enclosed places like the lagoon of Venice. However, the algal material gathered creates the additional problem of disposal because it contains large amounts of water to make direct incineration inapplicable. Open-air drying causes fermentation and the formation of smelly gases.
Therefore, biological treatment for converting the algal material into biogas and fertilizers, or for drying it and burning it in order to obtain iodide and other mineral salts utilized in agriculture or medicines, was proposed. However, such procedures require considerable equipment and energy consumption.
The technical and scientific literature of this century contains numerous studies and patents on the use of algae as a source of fibrous material for papermaking. However, the presence of many salts in the raw seaweed together with its low fibrous material content restricted development of paper or similar products based on fibrous material of algal origin because of the expensive process needed to recover the fibrous part of algae.
A process disclosed in EP-A-486486 describes production of pulp by directly using particular types of algae belonging to the Closterium genus and to Pleurotaenium genus. Those particular types of microalgae are from sweet water and contain cellulose, large amounts of hemicellulose, no lignin, and are very different from the macroalgae which are found in the sea (salt) water.